The present invention relates to an optical disk device in which information is recorded in both of grooves (which sometimes may be abbreviated as xe2x80x9cGxe2x80x9d) and lands (which may be abbreviated as xe2x80x9cLxe2x80x9d) in a spiral form about the axis of rotation of an optical disk which is a recording medium, and reproducing the recorded information, and in particular to a state detection device for detecting the state of an optical disk device based on an error detection code (IED) contained in a header of a recording sector of the optical disk, and an optical disk device using such a state detecting device to achieve recording and reproduction at a higher accuracy.
Recently, a standard of an optical disk (DVD-RAM) adopting a single spiral-land/groove (SS-L/G) recording format has been proposed, in which information is recorded in both of grooves and lands of a disk, in order to increase the recording density, and the land s and grooves are alternated every revolution to form a single continuous recording track. When this standard is adopted, the recording track pitch can be halved, provided that the groove pitch is unchanged, and there is therefore a great contribution to a higher density, and the products adopting this standard are believed to be promising.
The configuration of this optical disk is shown in FIG. 9 and FIG. 10. In the figure, grooves 104 are formed on the disk substrate, with the result that lands 105 are formed between the grooves 104, and a recording film 101 is formed thereon. Recording pits 102 are formed on both of the grooves 104 and lands 105 by a light spot which is scanned by an optical disk device, not shown. As shown in FIG. 10, tracks formed of the grooves 104 and lands 105 are alternated every revolution to form a single continuous recording track.
The optical disk is separated into a plurality of regions called zones (in the illustrated example, three zones Z1, Z2, Z3), and the number of recording sectors per revolution is constant within each zone, and is increased by a certain number, e.g., one, every transition from one zone to a radially outward, adjacent zone.
The track format of this disk is next described. FIGS. 11A and 11B show the configuration of the recording sectors of the optical disk. FIG. 11B is a schematic diagram showing the disposition of identification signals and address values in the recording sectors at a boundary, or connecting points, between lands and grooves. FIG. 11A is a schematic diagram showing the disposition of identification signals and address values in the recording sectors at parts other than the boundary (see ECMA/TC31/97/60).
In the drawings, each of identification information parts forming a header of a recording sector includes four address regions PID (physical ID) containing address information of the recording sector, and is formed of a front part (two PIDs in front) and a rear part (two PIDs at the back), with respect to the order of scanning of the light spot. The front part is shifted radially outward by half a track pitch, and the rear part is shifted radially inward by half a track pitch. In this connection, it is noted that the width of a groove is the same as the width of the land, and half a track pitch equals to the width of the groove. In this way, the front and rear parts are disposed in a staggering manner.
In FIG. 11A and FIG. 11B, it is assumed for the time being that the identification information part consists of PIDs. However, as will be later described with reference to FIG. 12, the identification information part additionally includes a region (VF0) containing information for PLL (phase-locked loop) control, a region (AM) containing synchronization information for address reproduction, and a region (IED) containing error detection codes for detection and correction of errors in the physical address.
The address of a recording sector in a groove is included in the rear part of the identification information part immediately preceding a user information part in the recording sector, and shifted radially inward by half a track pitch from the center of the groove track, while the address of a recording sector in a land is included in the front part of the identification information part immediately preceding the user information part, and shifted radially inward by half a track pitch from the center of the land track (and hence shifted radially outward by half a track pitch from the center of the groove track, which is radially inward of and adjacent to the land track in question).
The identification information is shifted by half a track pitch from the center of the track because this enables the identification information to be shared between a groove track and a land track adjacent to each other, so that the identification information of equal quality can be read whichever of a groove track or a land track is being scanned.
As explained above, FIG. 11B shows the disposition of identification signals at a boundary, and address values represented by the identification signals. As shown in FIG. 10, there is a radially extending boundary line at which groove tracks and land tracks are connected.
The connecting point is detected for example in t he following manner. In a state in which a tracking is achieved, the directions of shifting of the front and rear parts of the identification information part can be detected by referring to the tracking error signal. That is, if the tracking error signal indicates a radially inward tracking error in the front part, and then a radially outward tracking error in the rear part (which means that the front part of the identification information part is deviated radially outward and the rear part is deviated radially inward with reference to the scanning light spot), then the light spot is recognized as scanning a groove track. In contrast, if the tracking error signal indicates a radially outward tracking error in the front part, and then a radially inward tracking error in the rear part (which means that the front part is deviated radially inward and the rear part is deviated radially outward with reference to the scanning light spot), then the light spot is recognized as scanning a land track.
The address read from the identification information part is related to each sector in the following manner. That is, the rear part of the identification information part shifted radially inward by half a track pitch contains the address of a sector (groove sector) in a groove track, and the front part of the identification information part shifted radially outward by half a track pitch contains the address of a sector (land sector) in a land track.
An optical disk device which records and reproduces information in and from an optical disk of the above described configuration judges which of a groove track and a land track is being scanned on the basis of the tracking error signal, and recognizes the information obtained from the rear part of the identification signal as the address of the sector when a groove track is judged to be scanned, and recognizes the information obtained from the front part of the identification signal as the address of the sector when a land track is judged to be scanned.
FIG. 12 shows details of the identification information part. The identification information part is comprised of header regions H1-H4. Each of the header regions H1 to H4 includes a VFO, AM (address mark regions), PID (address region), and IED (address error detection region), and PA (post-amble region). The VFO, AM, PID, IED, and PA are associated with suffixes 1 to 4, depending on which of the four header regions H1 to H4, they belong to. The reference marks VFO, AM, PID, IED, and PA are used not only for denoting the regions, but also the information or signals read from the respective regions.
The VFO is a region of a single frequency pattern used for generation of a synchronous clock and detection timing signals during reproduction. These are used in pull-in operation of a PLL which generates read channel bit clock used during reproduction of signals. The AM is used for reading data in the header region, and is detected by pattern matching of a unique channel bit pattern of the AM, and is used for generation of timing signals, and identification of the boundary between bytes.
The PID contains the address information of the recording sector, the sector information (indicating the order within the four PIDs, i.e., which of the four PIDs the PID in question is, or indicating whether the sector is at the head of a track, or at the end of a track). The IED is appended to the PID for detecting any error in the PID having been read. The PID and IED are modulated, and the PA indicates the end of the modulation.
In the DVD-RAM, four address regions PID1 to PID4 are provided. Each of the address regions PID1 and PID2 contains the address of the recording sector in the groove track. That is, the same address is written repeatedly or in duplication. Each of the address regions PID3 and PID4 contains the address of the recording sector in the land track. That is, the same address is written repeatedly or in duplication.
As shown in FIG. 11A and FIG. 11B, the PID1 and PID2 are shifted radially outward from the center of the groove track by about p/2 (p being the track pitch), and the PID3 and PID4 are shifted radially inward from the center of the groove track by about p/2.
FIG. 13 shows part of an optical disk device for identifying the PID for the recording sector being scanned.
In FIG. 13, PID1 to PID4 denote the signals indicating the address values read from the respective PID regions (also denoted by PID1 to PID4). IED10K to IED40K indicate the result of the error correction detection by means of the signals IED1 to IED4.
A coincidence judgment circuit 106 determines whether PID1 and PID2 input thereto are identical with each other. A coincidence judgment circuit 107 determines whether PID3 and PID4 input thereto are identical with each other. When information is recorded or reproduced from an optical disk in which the address arrangement is as shown in FIG. 11A and FIG. 11B, the addresses PID1 and PID2 which are the addresses of the same groove sector written in duplication, should be identical if they are read correctly. The coincidence judgment circuit 106 ascertains this. The addresses PID3 and PID4 which are the addresses of the same land sector written in duplication, should be identical if they are read correctly. The coincidence judgment circuit 107 ascertains this.
If however the PID1 and PID2 are not read correctly, it is necessary to find which of PID1 and PID2 is correct, or substitute an address value when neither of PID1 and PID2 seems correct or is reliable. Similarly, if the PID3 and PID4 are not read correctly, it is necessary to find which of PID3 and PID4 is correct, or substitute an address value when neither of PID3 and PID4 seems correct or is reliable.
A PID selector 108 selects one of PID1 and PID2, according to its judgment on which of PID1 and PID2 is correct or more reliable, based on IED10K and IED10K, and outputs the selected one of PID1 and PID2 as well as a reliability signal RLB1 indicating the reliability (as to the correctness) of the selected output. This judgment is made using a judgment table 203. FIG. 14A shows the manner of selection between PID1 and PID2.
In FIG. 14A, xe2x80x9cHxe2x80x9d in column CIC1 indicates that PID1 and PID2 have been found identical, while xe2x80x9cLxe2x80x9d in column CIC1 indicates PID1 and PID2 have not been found identical. xe2x80x9cLxe2x80x9d in column IED10K indicates IED10K is true, while xe2x80x9cHxe2x80x9d in column IED10K indicates IED10K is not true. xe2x80x9cLxe2x80x9d in column IED20K indicates IED20K is true, while xe2x80x9cHxe2x80x9d in column IED20K indicates IED20K is not true. xe2x80x9cHxe2x80x9d in column RLB1 indicates that the value of the selected PID is reliable, while xe2x80x9cLxe2x80x9d in column RLB1 indicates that the value of the selected PID is not reliable.
When the coincidence signal CIC1 from the coincidence judgment circuit 106 is at xe2x80x9cHxe2x80x9d indicating that PID1 and PID2 are identical (cases Nos. 5 to 8), either of PID1 and PID2 may be selected. In the table shown in FIG. 14A, PID2 is selected. This applies regardless of either of IED10K and IED20K is at xe2x80x9cHxe2x80x9d indicating that PID1 or PID2 has not been correctly read (cases Nos. 6 to 8).
When the coincidence signal CIC1 from the coincidence judgment circuit 106 is at xe2x80x9cLxe2x80x9d indicating that PID1 and PID2 are not equal (cases Nos. 1 to 4), if IED10K is at xe2x80x9cLxe2x80x9dindicating that the PID1 has been read correctly (case No. 2), PID1 is selected, while if IED20K is at xe2x80x9cLxe2x80x9d indicating that the PID2 has been read correctly (case No. 3), PID2 is selected. If IED10K and IED20K are both at xe2x80x9cLxe2x80x9d (case No. 1) or both at xe2x80x9cHxe2x80x9d (case No. 4), either of PID1 and PID2 is selected. In the table shown in FIG. 14A, PID2 is output.
The reason why the PID2 is selected in such a case is that the likelihood of PID2 being correct is higher because the re-synchronization is initiated at the beginning of each identification information area, and there is a longer time for stabilization after the initiation of the re-synchronization before PID2 appears than before PID1 appears.
When IED10K and IED20K are both at xe2x80x9cHxe2x80x9d indicating that neither of PID1 and PID2 have been correctly read (cases Nos. 4 and 8), the reliability signal RLB1 is at xe2x80x9cLxe2x80x9d indicating that the reliability is low. In other cases, the reliability signal RLB1 is at xe2x80x9cHxe2x80x9d indicating that the reliability is high.
In an alternative arrangement, the reliability signal RLB1 is at xe2x80x9cHxe2x80x9d only when IED10K and IED20K are both at xe2x80x9cHxe2x80x9d and the coincidence signal CIC1 is at xe2x80x9cHxe2x80x9d indicating that PID1 and PID2 are not equal (case No. 4), and the reliability signal RLB1 is at xe2x80x9cLxe2x80x9d when the coincidence signal CIC1 from the coincidence judgment circuit 106 is at xe2x80x9cLxe2x80x9d (case No. 8).
A PID selector 109 selects one of PID3 and PID4, according to its judgment on which of PID3 and PID4 is correct or more reliable, based on IED30K and IED40K, and outputs the selected one of PID3 and PID4 as well as a reliability signal RLB2 indicating the reliability (as to the correctness) of the selected output. This judgment is made using a judgment table 204. FIG. 14B shows the manner of selection between PID3 and PID3.
In FIG. 14B, xe2x80x9cHxe2x80x9d in column CIC2 indicates that PID3 and PID4 have been found identical, while xe2x80x9cLxe2x80x9d in column CIC2 indicates PID3 and PID4 have not been found identical. xe2x80x9cLxe2x80x9d in column IED30K indicates IED30K is true, while xe2x80x9cHxe2x80x9d in column IED30K indicates IED30K is not true. xe2x80x9cLxe2x80x9d in column IED40K indicates IED40K is true, while xe2x80x9cHxe2x80x9d in column IED40K indicates IED40K is not true. xe2x80x9cHxe2x80x9d in column RLB2 indicates that the value of the selected PID is reliable, while xe2x80x9cLxe2x80x9d in column RLB2 indicates that the value of the selected PID is not reliable.
The operation of the PID selector 109 is shown in FIG. 14B, and is similar to that of the PID selector 108 except that PID1, PID2, IED10K, IED20K, CIC1, and RLB1 are replaced by PID3, PID4, IED30K, IED40K and CIC2, and RLB2, respectively.
A sector address selector 110 receives two signals (selected PID and reliability signals RLB1) from the PID selector 108, and two signals (selected PID (PID3 or PID4) and reliability signal RLB2) from the PID selector 109, as well as a sector number signal N, and a land/groove signal L/G, and selectively outputs a sector address.
The sector number signal N indicates the number N of sectors per track and is supplied from an MPU (microprocessor) forming part of a system controller, not shown, which controls the entire optical disk device, and manages the number of sectors per track.
The land/groove signal L/G indicates whether the track being scanned is a groove track or a land track, and is produced based on the result of detection as to the direction of shift of the front and rear pars of the identification information area with respect to the center of the track, i.e., with respect to the light spot in a state in which the tracking is established.
Let us first assume that the track being scanned is known to be a groove track, according to the land/groove signal L/G. When the reliability signal RLB2 is at xe2x80x9cHxe2x80x9dindicating that the output of the PID selector 109 is reliable, the sector address selector 110 selects the output of the PID selector 109 as the address of the groove sector. When the reliability signal RLB2 is at xe2x80x9cLxe2x80x9d indicating that the output of the PID selector 109 is not reliable, and the reliability signal RLB1 is at xe2x80x9cHxe2x80x9d indicating that the output of the PID selector 108 is reliable, the sector address selector 110 subtracts the number N of sectors per track from the output of the PID selector 108, and outputs the difference (the result of the subtraction) as the address of the groove sector.
When the reliability signals RLB1 and RLB2 are both at xe2x80x9cLxe2x80x9d, a substitute sector is used.
Let us next assume that the track being scanned is known to be a land track, according to the land/groove signal L/G. When the reliability signal RLB1 is at xe2x80x9cHxe2x80x9d indicating that the output of the PID selector 108 is reliable, the sector address selector 110 selects the output of the PID selector 108 as the address of the land sector. When the reliability signal RLB1 is at xe2x80x9cLxe2x80x9d indicating that the output of the PID selector 108 is not reliable, and the reliability signal RLB2 is at xe2x80x9cHxe2x80x9d indicating that the output of the PID selector 109 is reliable, the sector address selector 110 adds the number N of sectors per track to the output of the PID selector 109, and outputs the sum (the result of the addition) as the address of the land sector. When the reliability signals RLB1 and RLB2 are both at xe2x80x9cLxe2x80x9d, then a substitute sector is used.
When the above described method is adopted, if at least one of the four PIDs is correctly read, the address of the sector being scanned can be identified correctly. However, it is necessary to provide a circuit which performs the subtraction of the number N of sectors. This means that the size of the circuit, or the number of gates, is increased. Moreover, it is necessary to ensure that the correct number N of the sectors per track be supplied.
In the optical disk device described above, the timing of starting, such as a timing at which recording is started, or a timing at which reproduction is started is determined based on the state of the detected synchronous signal or the state of the error correction code in the reproduced signal.
In such an arrangement, in the event of a disturbance from outside of the optical disk device, an erroneous judgment that the starting is not possible may be made when in fact it is possible, or an erroneous judgment that the starting is possible may be made when in fact it is not possible. This makes it difficult to improve the accuracy at which information is recorded or reproduced.
Another problem associated with the conventional optical disk device relates to gate (window) signals. Various gate signals are used for setting timings for recording, for extracting only headers from the reproduced data, or for removing headers from the reproduced data, and various other purposes. The gate signals are generated based on addresses read from the headers. But because the addresses read from the headers are not necessarily reliable when the optical disk device has just been started, the gate signals are not obtained at a high accuracy.
The present invention has been made to solve the problems described above, and its object is to provide a state detection device for detecting the state of the optical disk device at a high accuracy, and an optical disk device which can record information on and reproduce information from an optical disk of an SS-L/G format.
According to one aspect of the invention, there is provided a state detecting device for detecting a state of an optical disk device recording data in and reproducing data from an optical disk having a header information part for each sector, each header information part including a plurality of header regions each including an address region for holding address information, and address error detection region for holding an address error detection code for detecting an error in the address information read from the address region;
said state detecting device comprising:
header detecting means for detecting the header regions;
error detecting means for judging whether or not the error detection code read from the address error detection region included in the detected header region indicates an error in the address information read from the address region, and holding the number of errors for one sector;
error count comparing means for comparing the number of errors held in the error detecting means with a predetermined number; and
state judging means responsive to the output of the error count comparing means for causing transition to a higher or lower state, to thereby identify the state of the optical disk device.
With the above arrangement, recording and reproduction can be performed according to the state of the optical disk device, and hence more properly and with a higher accuracy.
The state judging means may be configured to cause transition to a higher state when the number of errors held in the error detecting means is not more than the predetermined value and causes transition to a lower state when the number of errors held in the error detecting means is more than the predetermined value.
The xe2x80x9cpredetermined valuexe2x80x9d used for comparison with the number of errors can be set taking account of the characteristics of the optical disk device, and the accuracy required of the optical disk device can be obtained with ease.
The state judging means may be configured to cause transition to a lower state when the number of errors held in the error detecting means continues to be more than the predetermined value for a predetermined number of sectors.
With the above arrangement, recording and reproduction can be achieved properly according to the characteristics of the optical disk.
The header detecting means may be configured to detect the header regions using a first header detection window generated based on the address information, or a second header detection window generated based on a header position detection signal indicating the arrangement of the plurality of header regions contained in one sector.
With the above arrangement, the manner of detecting the header regions which is associated with less errors can be selected according to the state of the optical disk device.
The header detecting means may be configured to detect the header regions using the first header detection window when the optical disk device is in or above a predetermined state, and detect the header regions using the second header detection window when the optical disk device is below the predetermined state.
According to another aspect of the invention, there is provided an optical disk device recording data in and reproducing data from an optical disk having a header information part for each sector, each header information part including a plurality of header regions each including an address region for holding address information and an address error detection region for holding an address error detection code for detecting an error in the address information read from the address region, comprising:
an optical head for writing data on and reading data from an optical disk device;
header detecting means for detecting the header region from the data read by the optical head;
header detecting means for detecting the header regions from the data read by the optical head;
error detecting means for judging whether or not the error detection code read from the address error detection region included in the detected header region indicates an error in the address information read from the address region, and holding the number of errors for one sector;
error count comparing means for comparing the number of errors held in the error detecting means with a predetermined number;
state judging means responsive to the output of the error count comparing means for causing transition to a higher or lower state, to thereby identify the state of the optical disk device; and
control means for controlling the recording and reproducing operation of the optical disk device in accordance with the result of the judgment by the state judging means.
With the above arrangement, the control over operation of the optical disk device can be made properly according to the state of the optical disk device.
The control means may be configured to permit recording of data from the optical disk when the optical disk device is in or above a predetermined state, and prohibit the recording and reproduction when the optical disk device is below said predetermined state.
With the above arrangement, recording and reproduction can be achieved with a high accuracy, and in particular erroneous overwriting, during recording, can be avoided.
The state judging means may be configured to cause transition to a lower state when the number of errors held in the error detecting means continues to be more than the predetermined value for a predetermined number of sectors.
With the above arrangement, recording and reproduction can be achieved properly according to the characteristics of the optical disk.
The header detecting means may be configured to detect the header regions using a first header detection window generated based on the address information, or a second header detection window generated based on a header position detection signal indicating the arrangement of the plurality of header regions contained in one sector.
With the above arrangement, the manner of detecting the header regions which is associated with less errors can be selected according to the state of the optical disk device.
The header detecting means may be configured to detect the header regions using the first header detection window when the optical disk device is in or above a predetermined state, and detect the header regions using the second header detection window when the optical disk device is below the predetermined state.
With the above arrangement, errors in detecting the header regions can be reduced even when the optical disk device has just been started, or when the address information cannot be obtained stably for some other reason.
According to a further aspect of the invention, there is provided an optical disk device for recording data in and reproducing data from an optical disk having a header information part for each sector, the header information part including a plurality of header regions, a front part of the header information part being shifted from the center of a track by half a track pitch in one of a radially inward and radially outward directions, and a rear part of the header information part being shifted from the center of a track by half a track pitch in the other of a radially inward and radially outward directions,
the optical disk device comprising:
an optical head forming a light spot for writing data in and reading data from an optical disk;
an analog signal processor responsive to the output of the optical head for producing a reproduced signal and a tracking error signal;
address signal generating means for generating address information indicating the position within the sector based on the output of the analog signal processor at the time when the light spot passes the header regions on the optical disk; and
window generating means responsive to the address information indicating the position within the sector, for generating a detection window signal or a timing signal.
With the above arrangement, detection windows (gate signals) and timing signals of high accuracy can be produced.
According to a further aspect of the invention, there is provided an optical disk device recording data in and reproducing data from an optical disk having a header information part for each sector, each header information part including a plurality of header regions each including an address region for holding address information and an address error detection region for holding an address error detection code for detecting an error in the address information read from the address region; a front part of the header information part being shifted from the center of a track by half a track pitch in one of a radially inward and radially outward directions, and a rear part of the header information part being shifted from the center of a track by half a track pitch in the other of a radially inward and radially outward directions, an optical head for forming a light spot for writing data on and reading data from the optical disk;
header detecting means for detecting header regions from the data read by the optical head;
error detecting means for detecting any error present in the address information having been read, based on an error detection code contained in the header region detected; and
window generating means for generating a window signal or a timing signal based on the address information indicating the position within the sector, when it is found by the error detecting means that the address information have been correctly read.
With the above arrangement, detection windows (gate signals) and timing signals which are satisfactory for practical purposes can be obtained even when the optical disk device has just been started, or when the address information cannot be obtained stably for some other reason.
According to a further aspect of the invention, there is provided an optical disk device recording data in and reproducing data from an optical disk having a header information part for each sector, each header information part including a plurality of header regions each including an address region for holding address information and an address error detection region for holding an address error detection code for detecting an error in the address information read from the address region; a front part of said header information part being shifted from the center of a track by half a track pitch in one of a radially inward and radially outward directions, and a rear part of said header information part being shifted from the center of a track by half a track pitch in the other of a radially inward and radially outward directions, comprising:
an optical head for forming a light spot for writing data on and reading data from an optical disk;
an analog signal processor responsive to the output of the optical head for producing a reproduced signal and a tracking error signal;
header detecting means for detecting the header regions from the data read by the optical head;
error detecting means for judging whether or not the error detection code read from the address error detection region included in the detected header region indicates an error in the address information read from the address region, and holding the number of errors for one sector;
error count comparing means for comparing the number of errors held in the error detecting means with a predetermined number;
state judging means responsive to the output of the error count comparing means for causing transition to a higher or lower state, to thereby identify the state of the optical disk device; and
window generating means for generating a detection window signal or a timing signal based on the address information contained in the header region detected, when the result of judgment by the state judging means indicates that the optical disk device is in or above a predetermined state, and for generating a detection window signal or a timing signal based on address information which indicates the position within the sector and is generated based on the output of the optical analog signal processor at the time when the light spot passes the header region, when the result of judgment by the state judging means indicates that the optical disk device is below the predetermined state.
With the above arrangement, detection windows (gate signals) and timing signal which are satisfactory for practical purposes can be obtained even when the optical disk device has just been started, or when the address information cannot be obtained stably for some other reason. On the other hand, when the address information can be reproduced stably from the header regions, detection windows (gate signals) and timing signals of high accuracy can be used. Thus, whatever the state of the optical disk device is, the detection windows (gate signals) and timing signals which are more suitable to the state of the optical disk device can be generated.
The header detecting means may be configured to detect said header regions using a header detection window generated by the window generating means.
With the above arrangement, whatever the state of the optical disk device is, the detection windows (gate signals) and timing signals which are more suitable to the state of the optical disk device can be generated.